RifleFanatic -
Yeah, could be the reason. Best I remember a 22LR will fire in the '03 Auto but will not properly work the action, extract/eject, etc. The '03 Auto ammo was purposely made slightly larger so it wouldn't fit in the older 22's designed for black powder cartridges. I had an '03 back in the mid 1960's. Got to where I couldn't find ammo for it so wrote to Winchester about having it modified to shoot 22LR. They replied that it couldn't be done. Was later talking to the 'smith at Southwest Shooters in Oklahoma City about it and he said he'd done several. Don't remember exactly what he did about the internals but he replaced the '03 barrel with one from a Mod 63 and that thing shot like a house afire. Think it cost me around fifty bucks at the time (the modification that is; I picked up the rifle for near nothing; was an E-4 in the Air Force at the time and we didn't "make no money honey"

). I kept the rifle for several years afterward and shot lots of squirrels with it. Being short of cash one day (nothing unusual in those days), I finally sold it to a guy who wanted it more than I

. I've had for many years a nice old 1939 vintage Model 63 (born same year as me) that I dearly love but I still regret selling the old '03.